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Title: The unperturbed oxo-sulfido functional group cis-Mo{sup VI}OS related to that in the xanthine oxidase family of molybdoenzymes: Synthesis, structural characterization, and reactivity aspects

Abstract

The oxo-sulfido functional group cis-Mo{sup VI}OS is essential to the activity of the xanthine oxidase family of enzymes but has proven elusive to synthesis in molecules containing no other four-electron ligands. A direct route to molecules containing this group has been achieved. The reaction system [MoO{sub 2}(OSiPh{sub 3}){sub 2}]/L in dichloromethane yields the complexes [Mo{sup VI}O{sub 2}(OSiPh{sub 3}){sub 2}L] (L = phen (1), Me{sub 4}phen (2), 4,4{prime}-Me{sub 2}bpy (3), 5,5{prime}-Me{sub 2}bpy (4), 2 py (5)) (74--96%), which are shown to have a distorted octahedral structure of crystallographically imposed C{sub 2} symmetry (1, 5) with cis oxo and trans silyloxy ligands. The related reaction system [MoO{sub 3}S]{sup 2{minus}}/2Ph{sub 3}SiCl/L in acetonitrile affords the complexes [Mo{sup VI}OS(OSiPh{sub 3}){sub 2}L] (L = phen (6), Me{sub 4}phen (7), 4,4{prime}-Me{sub 2}bpy (8), 5,5{prime}-Me{sub 2}bpy (9)) (36--69%). From the collective results of elemental analysis, mass spectrometry, {sup 1}H NMR, and X-ray structure determinations (6, 7), complexes 6--9 are shown to contain the cis-Mo {sup VI}OS group in molecules with the same overall stereochemistry as dioxo complexes 1--5. The crystal structures of 6 and 7 exhibit O/S disorder, which was modeled in refinements with 50% site occupancies. The Mo{double{underscore}bond}O (1.607(5) (6), 1.645(5) (7) {angstrom}) and Mo{double{underscore}bond}S (2.257(3)more » (6), 2.203(2) (7) {angstrom}) bond distances obtained in this way are somewhat shorter and longer, respectively, than expected. Distances obtained by molybdenum EXAFS analysis using the GNXAS protocol for 6--9 (Mo{double{underscore}bond}O 1.71--1.72 {angstrom}; Mo{double{underscore}bond}S 2.18--2.19 {angstrom}) are considered more satisfactory and are in good agreement with EXAFS values for xanthine oxidase. Molybdenum K-edge data for 1 and 6--9 are reported. Reaction of 7 with Ph{sub 3}P in dichloromethane results in sulfur abstraction and formation of [Mo {sup V}OCl(OSiPh{sub 3}){sub 2}(Me{sub 4}phen)] (10), which has a distorted octahedral structure with cis O/Cl and cis silyloxy ligands. Sulfur rather than oxygen abstraction is favored by relative Mo{double{underscore}bond}O/Mo{double{underscore}bond}S bond strengths. Complexes 6--9 should allow exploration of the biologically significant cis-Mo {sup VI}OS group.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Harvard Univ., Cambridge, MA (US)
Sponsoring Org.:
National Science Foundation; National Institutes of Health; Swedish Natural Research Council; US Department of Energy
OSTI Identifier:
20000073
Alternate Identifier(s):
OSTI ID: 20000073
Resource Type:
Journal Article
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 38; Journal Issue: 18; Other Information: PBD: 6 Sep 1999; Journal ID: ISSN 0020-1669
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; XANTHINES; ENZYMES; PTERIDINES; MOLYBDENUM; MOLYBDENUM COMPOUNDS; SULFUR OXIDES; CRYSTAL STRUCTURE; REACTIVITY

Citation Formats

Thapper, A., Donahue, J.P., Musgrave, K.B., Willer, M.W., Nordlander, E., Hedman, B., Hodgson, K.O., and Holm, R.H. The unperturbed oxo-sulfido functional group cis-Mo{sup VI}OS related to that in the xanthine oxidase family of molybdoenzymes: Synthesis, structural characterization, and reactivity aspects. United States: N. p., 1999. Web. doi:10.1021/ic990440v.
Thapper, A., Donahue, J.P., Musgrave, K.B., Willer, M.W., Nordlander, E., Hedman, B., Hodgson, K.O., & Holm, R.H. The unperturbed oxo-sulfido functional group cis-Mo{sup VI}OS related to that in the xanthine oxidase family of molybdoenzymes: Synthesis, structural characterization, and reactivity aspects. United States. doi:10.1021/ic990440v.
Thapper, A., Donahue, J.P., Musgrave, K.B., Willer, M.W., Nordlander, E., Hedman, B., Hodgson, K.O., and Holm, R.H. Mon . "The unperturbed oxo-sulfido functional group cis-Mo{sup VI}OS related to that in the xanthine oxidase family of molybdoenzymes: Synthesis, structural characterization, and reactivity aspects". United States. doi:10.1021/ic990440v.
@article{osti_20000073,
title = {The unperturbed oxo-sulfido functional group cis-Mo{sup VI}OS related to that in the xanthine oxidase family of molybdoenzymes: Synthesis, structural characterization, and reactivity aspects},
author = {Thapper, A. and Donahue, J.P. and Musgrave, K.B. and Willer, M.W. and Nordlander, E. and Hedman, B. and Hodgson, K.O. and Holm, R.H.},
abstractNote = {The oxo-sulfido functional group cis-Mo{sup VI}OS is essential to the activity of the xanthine oxidase family of enzymes but has proven elusive to synthesis in molecules containing no other four-electron ligands. A direct route to molecules containing this group has been achieved. The reaction system [MoO{sub 2}(OSiPh{sub 3}){sub 2}]/L in dichloromethane yields the complexes [Mo{sup VI}O{sub 2}(OSiPh{sub 3}){sub 2}L] (L = phen (1), Me{sub 4}phen (2), 4,4{prime}-Me{sub 2}bpy (3), 5,5{prime}-Me{sub 2}bpy (4), 2 py (5)) (74--96%), which are shown to have a distorted octahedral structure of crystallographically imposed C{sub 2} symmetry (1, 5) with cis oxo and trans silyloxy ligands. The related reaction system [MoO{sub 3}S]{sup 2{minus}}/2Ph{sub 3}SiCl/L in acetonitrile affords the complexes [Mo{sup VI}OS(OSiPh{sub 3}){sub 2}L] (L = phen (6), Me{sub 4}phen (7), 4,4{prime}-Me{sub 2}bpy (8), 5,5{prime}-Me{sub 2}bpy (9)) (36--69%). From the collective results of elemental analysis, mass spectrometry, {sup 1}H NMR, and X-ray structure determinations (6, 7), complexes 6--9 are shown to contain the cis-Mo {sup VI}OS group in molecules with the same overall stereochemistry as dioxo complexes 1--5. The crystal structures of 6 and 7 exhibit O/S disorder, which was modeled in refinements with 50% site occupancies. The Mo{double{underscore}bond}O (1.607(5) (6), 1.645(5) (7) {angstrom}) and Mo{double{underscore}bond}S (2.257(3) (6), 2.203(2) (7) {angstrom}) bond distances obtained in this way are somewhat shorter and longer, respectively, than expected. Distances obtained by molybdenum EXAFS analysis using the GNXAS protocol for 6--9 (Mo{double{underscore}bond}O 1.71--1.72 {angstrom}; Mo{double{underscore}bond}S 2.18--2.19 {angstrom}) are considered more satisfactory and are in good agreement with EXAFS values for xanthine oxidase. Molybdenum K-edge data for 1 and 6--9 are reported. Reaction of 7 with Ph{sub 3}P in dichloromethane results in sulfur abstraction and formation of [Mo {sup V}OCl(OSiPh{sub 3}){sub 2}(Me{sub 4}phen)] (10), which has a distorted octahedral structure with cis O/Cl and cis silyloxy ligands. Sulfur rather than oxygen abstraction is favored by relative Mo{double{underscore}bond}O/Mo{double{underscore}bond}S bond strengths. Complexes 6--9 should allow exploration of the biologically significant cis-Mo {sup VI}OS group.},
doi = {10.1021/ic990440v},
journal = {Inorganic Chemistry},
issn = {0020-1669},
number = 18,
volume = 38,
place = {United States},
year = {1999},
month = {9}
}